Pain Therapeutics Oxytrex Trial Fails To Cut Addiction In Statistically Meaningful Fashion

SOUTH SAN FRANCISCO, Calif., Nov. 22 /PRNewswire-FirstCall/ -- Pain Therapeutics, Inc. (Nasdaq: PTIE - News), a biopharmaceutical company, today announced results of a 775-patient Phase III trial with Oxytrex, an investigational drug candidate. The pre-defined primary endpoint was reduction in physical dependency, as measured by SOWS. The Company expected Oxytrex to reduce physical dependency by 25% or more. In this trial, Oxytrex reduced physical dependency by 28% compared to an equivalent dose of oxycodone but this result did not reach statistical significance due to high drop-out rates in all study arms.

Nadav Friedmann, PhD, MD, Chief Operating and Medical Officer at Pain Therapeutics, stated, "This is the second of two large trials designed to examine opioid-related physical dependency. We see a consistent and positive clinical response in the two trials. We are highly encouraged by the promise of the science, however, in today's trial we believe the signal was lost in the noise. There are ways to design clinical trials that overcome the statistical limitations imposed by very high drop-out rates. We expect to discuss these methodologies with the FDA in early 2006."

Pain Therapeutics anticipated that up to 40% of patients would drop-out before completing the study's three-month treatment period. Actual drop-out rates were 48% to 60% in the drug arms and 37% in the placebo arm. The number of patients completing the study was lower than expected and, given the statistical rigor of the study design, statistical significance was not reached in the primary endpoint.

"We believe the weight of all evidence, including prior clinical and non-clinical data, continues to favor Oxytrex over oxycodone," said Remi Barbier, President & CEO of Pain Therapeutics. "We remain steadfast to the Oxytrex program and its ability to reduce physical dependency."

Remi Barbier added, "We also note that today's clinical news does not impede the closing of our recently announced strategic alliance with King Pharmaceuticals, Inc. We expect to enter 2006 with over $200 million of cash, thanks to proceeds from this alliance. Preliminarily, we believe our net cash burn rate may be under $15 million in 2006, subject to final budget approvals."

Trial Design

Over 775 patients with moderate-to-severe osteoarthritic pain were enrolled in this randomized, double-blind, multi-center U.S. study. Patients received a fixed dose of drug (20mg or 40mg) or matching placebo for 12 weeks. Following a washout period, patients were randomized to one of six arms, each arm enrolling 150 patients except as noted: Oxytrex 10mg BID; Oxytrex 20mg BID; Oxytrex 10mg QID; oxycodone 10mg QID; ultra-low-dose naltrexone alone (N=75); or placebo (N=75).

The prospectively defined primary endpoint was reduction of physical dependence and withdrawal effects in the first 24 hours following cessation of therapy, as measured on the Short Opioid Withdrawal Scale (SOWS), between patients receiving Oxytrex 20mg BID and oxycodone 10mg QID (i.e., patients in both arms received a total daily drug dose of 40mg).

The secondary endpoint in this study was prospectively defined as non-inferior analgesic efficacy (pain relief) of Oxytrex 20mg BID versus oxycodone 10mg QID. 'Non-inferior analgesic efficacy' means patients on Oxytrex had to report equal or better pain relief than patients on oxycodone.

Trial Results

In the pre-defined primary endpoint, Oxytrex patients reported 28% less clinical symptoms of physical dependence and withdrawal effects in the first 24 hours following cessation of therapy, compared to patients on oxycodone. This result did not reach statistical significance. The trial did report statistical significance in a sub-group analysis: Oxytrex reduced physical dependency by 75% (p=0.04) in patients over 50 years of age.

The study met its pre-defined secondary endpoint. During the three-month treatment period, Oxytrex was non-inferior to oxycodone. Oxytrex patients reported slightly better pain relief than oxycodone patients and significantly better analgesia than placebo patients (p<0.05). In contrast, oxycodone did not separate from placebo, given the high drop-out rate and placebo response.

Corporate Update

Pain Therapeutics' recently announced a strategic alliance with King Pharmaceuticals, Inc. to develop and commercialize Remoxy(TM), a long-acting oral oxycodone, and other abuse-resistant opioid painkillers. Terms include an upfront cash payment of $150 million to Pain Therapeutics, payable upon closing of the alliance. We believe the alliance will close in 2005, subject to anti-trust and other regulatory reviews.

Pain Therapeutics remains on-track to announce in December results of a 600-patient Phase III trial with PTI-901 in women with Irritable Bowel Syndrome.

Conference Call

Pain Therapeutics will host a conference call for the investment community on Tuesday, November 22, 2005 at 10:00 a.m. ET to discuss this announcement. To participate in the conference call, please dial 800-659-1966 (within the U.S.) or 617-614-2711 (outside the U.S.) fifteen minutes prior to the start of the call. The call reference number is 38909448. A playback of the conference call will be available following the call. To access the playback, please dial 888-286-8010 (within the U.S.) or 617-801-6888 (outside the U.S.) and enter reservation number 12338816. A webcast of the conference call will also be available online at

About Pain Therapeutics, Inc.

Pain Therapeutics is an emerging biopharmaceutical company that develops novel drugs. Our investigational drug candidates target different types of chronic pain, such as low-back pain, pain due to osteoarthritis or irritable bowel syndrome. Pain Therapeutics has three unique drugs in Phase III clinical development: Remoxy(TM), Oxytrex and PTI-901. For more information please visit our website:

Note Regarding Forward-Looking Statements: This press release contains forward-looking statements for purposes of the Private Securities Litigation Reform Act of 1995 (the "Act"). PTI disclaims any intent or obligation to update these forward-looking statements, and claims the protection of the Safe Harbor for forward-looking statements contained in the Act. Examples of such statements include, but are not limited to, any statements relating to the timing and scope of the Company's clinical development of Oxytrex or PTI-901, the Company's anticipated discussions with the FDA, the potential benefits of Oxytrex and the Company's drug candidates, the Company's cash position at the end of 2005 and the Company's anticipated cash usage in 2006. Such statements are based on management's current expectations, but actual results may differ materially due to various factors. Such statements involve risks and uncertainties, including, but not limited to, those risks and uncertainties relating to difficulties or delays in development, testing, regulatory approval, production and marketing of Oxytrex and the Company's drug candidates, unexpected adverse side effects or inadequate therapeutic efficacy of the Company's drug candidates, including Oxytrex, that could slow or prevent clinical development, product approval or market acceptance (including the risk that current and past results of clinical trials are not necessarily indicative of future results of clinical trials), the uncertainty of patent protection for the Company's intellectual property or trade secrets, the Company's ability to obtain additional financing if necessary and unanticipated research and development and other costs. For further information regarding these and other risks related to the Company's business, investors should consult the Company's filings with the Securities and Exchange Commission.

Source: Pain Therapeutics, Inc.

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